An important endodontic procedure, known as a “root canal” procedure, involves removing organic material from the root canals of an infected tooth and filling the canal with an inert obturating material such as gutta percha gum.
An effective root canal procedure avoids extraction of the infected tooth. In this procedure, a dentist or endodontist utilizes a series of endodontic instruments, for example files, for the debridement, cleaning and sterilization of the root canal. These files are rotated within the canal to clean the canal surfaces, removing debridement (organic) material in the process, facilitating improved irrigation, and in some cases shaping the canal for easier filling with the obturating material.
The purpose of a canal preparation is to remove all organic debris and infected material from within the canal. The canal preparation is widely accomplished with engine-driven instruments. During the canal preparation, an irrigant is dispensed in the canal in order to help removing the debris created by the abrading action of endodontic instruments, and also promoting disinfection of the root canal space by flushing out microbes. The irrigant may be water or a chemical solution, or a combination thereof.
Once the pulp has been removed from the root canal, a smear layer remains. The smear layer is potentially infected, and its removal allows more efficient penetration of intracanal medications into the dentinal tubules and a better interface between the filling material and the root canal walls. A final flush with chelating agents and antiseptic irrigating solutions is needed to remove the smear layer. However, the effectiveness of these chelating agents and antiseptic irrigating solutions remains limited especially in areas with a complex anatomy such as isthmuses. Therefore, the improvement of irrigating protocols is essential during root canal treatment in order to achieve better cleaning efficiency.
Numerous techniques and irrigating solutions have been described to accomplish the final irrigation. However, due to the complexity of the root canal anatomy, typically at least 40% of the root canal surface remains untouched by the endodontic instruments and unaffected by the irrigants, as shown in several high-definition micro-computed tomography and histological studies, respectively: Peters et al. 2001; Pape et al. 2010; Versiani et al. 2011, 2013, De-Deus et al. 2010; each of which is incorporated by reference in its entirety. Organic and infected debris always remain in the canal space (Vera et al. 2012). Most importantly, the organic inner layer of dentine (called “predentine”) covering the wall of the root canal, which is usually heavily infected, will typically be untouched by endodontic instruments and irrigant. The remaining infected debris and the untouched infected predentine layer might adversely affect the final outcome of the root canal treatment; the bacteria remaining in the obturated canal space will use the organic material for nutrition and will re-colonize the obturated canal space leading to a failed root canal treatment (Nair et al. 2005).
The ability of an irrigant to act in these hard-to-reach areas depends mainly on the delivery method. See for example: Brito P R 1, Souza L C, Machado de Oliveira J C, Alves F R, De-Deus G, Lopes H P, Siqueira J F Jr. Comparison of the effectiveness of three irrigation techniques in reducing intracanal Enterococcus faecalis populations: an in vitro study. J Endod. 2009 October; 35(10):1422-7; De-Deus G, Barino B, Zamolyi R Q, Souza E, Fonseca A Jr, Fidel S, Fidel R A. Suboptimal debridement quality produced by the single-file F2 ProTaper technique in oval-shaped canals. J Endod. 2010 November; 36(11):1897-900; Gulabivala K, Ng Y L, Gilbertson M, Eames I. The fluid mechanics of root canal irrigation. Physiol Meas. 2010 December; 31(12):R49-84; Nair P N 1, Henry S, Cano V, Vera J. Microbial status of apical root canal system of human mandibular first molars with primary apical periodontitis after “one-visit” endodontic treatment. Oral Surg Oral Med Oral Pathol Oral Radiol Endod. 2005 February; 99(2):231-52; Peters O A, Sch8nenberger K, Laib A. Effects of four Ni—Ti preparation techniques on root canal geometry assessed by micro computed tomography. Int Endod J. 2001 April; 34(3):221-30; Peters O A, Boessler C, Paque F. Root canal preparation with a novel nickel-titanium instrument evaluated with micro-computed tomography: canal surface preparation over time. J Endod. 2010 June; 36(6):1068-72; Vera J, Siqueira J F Jr, Ricucci D, Loghin S, Fernandez N, Flores B, Cruz A G. One-versus two-visit endodontic treatment of teeth with apical periodontitis: a histobacteriologic study. J Endod. 2012 August; 38(8):1040-52; Versiani M A, Pecora J D, de Sousa-Neto M D. Flat-oval root canal preparation with self-adjusting file instrument: a micro-computed tomography study. J Endod. 2011 July; 37(7):1002-7.
As noted above, one important object of conventional canal preparation and irrigation procedures is to clean the canal (remove the organic and infected material and the organic predentine layer). In order to achieve this objective, a series of endodontic instruments are used to enlarge the root canal space in a continuously tapered shape. The instruments used toward the end of the canal preparation have relatively large diameters and tapers, and are relatively rigid. The use of these larger instruments has been associated with several complications such as instrument fracture, canal ledging and transportation, root perforation and weakening of the tooth structure (potentially leading to root fracture), which can ultimately lead to the need to extract the tooth. Moreover, conventional mechanical enlargement techniques embrace long-standing learning curves in order to achieve the minimal standard in terms of efficacy and safety.
There is accordingly a need for an improved irrigation system and device that provides greater cleaning and disinfecting efficacy in a root canal.